Problem: Simplify the following expression: $k = \dfrac{5t + s}{6r} + \dfrac{4t}{6r}$ You can assume $r,s,t \neq 0$.
Solution: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{5t + s + 4t}{6r}$ $k = \dfrac{9t + s}{6r}$